Đáp án:
a, Ta có
`2/7`=`(2.5)/(5.7)`=`10/35`
`3/5`=`(3.7)/(5.7)`=`21/35`
Vì `21/35`>`10/35 nên `3/5`>`2/7`
b,Ta có:`-85/-93`=`85/93`>0
`-2/7`<0
=>`-85/-93`>`-2/7`
c, Vì `7/5`>1
` 496/572`<1
=>`7/5`>`496/572`
d, Ta có: `7/8`=`(7.30)/(8.30)`=`210/240`
Vì `210/240`>`210/243` nên `7/8`>`210/243`
e, Ta có:`53/57`=`530/570`=1-`40/70`
`531/571`=1-`40/71`
Vì `40/70`>`41/70`nên 1-`40/70`<1-`41/70`
hay `53/37`<`531/571`